Drainage of floating roofs



Oct. 15, 1935. E. E. sHANoR DRAINAGE OF FLOATING ROOFS Y Filed Dec. 21, 1932 4giuliana! oct. 15,1935

UNITED STATES PATENT ori-icas Application December 2l, 1932, Serial No. 648,282

5Claims.

The invention has to do more particularly with oil storage systems of the oating roofRtype. With such systems it has been, for many years, more` or less conventional practice to provide 5 facilities for draining excess accumulation of wa'- ter.k on `the roof such as may follow cloudbursts or Cunusually heavy rainfalls, it being obvious that the roof may collapse `or otherwise be seriously damaged by such sudden 'accession of weight. Some of these drainage practices are good and some are wholly impracticable and most of them'suierthe disadvantage that they are complicated and, hence, costly in installation and maintenance.

The principal object of the present invention is to provide for drainage of floating roofs in anV emcient and simple way' and inL such way as will appreciably reduce the cost of installation, obviate the necessityof frequent repairs and so appreciably reduce-the cost of upkeep; to provide for drainage via the uid content of the` storage -space and without the hazard of the fluid content, or its volatiles, making'egress through the drain.

The nature, characteristic features and scope of the invention more readily will be understood from the following'detailed description taken inr In the drawing, repre'sents the floating roof, K

the organization and details of which may be as usual except as' departed from in carrying the 4 invention into practice. E represents the collecting basin or sump which as usual may be clisposed axially of the floating deck or roof, or wherever there isprovision for natural drainage The sump or basin S-comprises a-bottom wall 5o i and a side wall vl connected `by weld deposit metal S, the side wallhaving a top offset i0 secured byweld deposit metal il and affording a ready tie to facilitate iield application to the deck .5 as by weld deposit metal I2.

55 The bottom wall of the sump is provided with l (Cl. 22o-26) I6` has co-extensive therewith an S strap I 8.

It is a merit. of the invention that the 'trap is inexpensively formed of duplicate semi-circular bends I9-and20 connected by weld deposit metal 2|. Bend I9 is joinedgmto the straight leg I6 by 10 weld deposit metal 22 and bend 2Ilhas a depending straight leg portion 23 joined thereto by weld deposit metal 24. Outlet 23 is adapted for the temporary reception of a cap 25. So also the .riser or straight pipe extension I 'I is provided 15 with a removable cap 26. The sleeve or collar I4 ranges upwar in the sump orbasin and is substantially the epth thereof and constitutes an overflow to lead excess drainage into the depending straight leg of the drainage system. Ele- 20 ment It is of relatively heavy or sturdy construction and lends strength and adequate support to the drainage system. It will be understood that when the system is properly functioning the riser or upper pipe extension il is re, 25 moved from the overiiow element.

In priming the drainage system, the caps on the terminalv end of the trap and on the head of the riser are removed and water is supplied to the drainage system up to a point indicated by the line X-X, whereupon the trap closure is replaced and screwed water-tight and the system is replenished with water until `it is practically iilled and the cap on the riser is replaced in airtight relation. The lower cap is then removed, V

the effect of which is to permit water to the right of line W-W t0 run out while, if the cap on the riser is in proper sealing relation, the water to the left of line W--W will remain in the drain.

The roof is now ready for oating.` When the roof oats there will be an air pocket at C. After the roof is floated, the cap on the riser isremoved and thealr pocket is .dissipated ori destroyed in any suitable way. One expedient which `has proven eminently satisfactory is to insert a sound or Searcher S comprising a straight stem or a rigid portion and a iiexible advanced portion and .an external valve or petcoclr V, through the medium of which the pocketed air is allowed to escape. The air remover is then detached and a check is made to see if the water in the drain has fallen below line Y--Y and if it has, the upper pipe e5 extension or riser l1 may be removed whereupon the drain is ready for operation.

It will be understood that this drain is to be used in cases where the contents of the tank consist of liquid lighter than water and for this reason a water seal or trap is employed to prevent the liquid from rising through the drain to the roof.

Crude oil, as it comes from the well, contains heavy sediment whiclrsettles to the bottom of the tank and is heavier than water and is known to the industry as B. 5.". When oil is being pumped into the tank/ the sediment circulates throughout the tank. 'If the drain is open toward the roof and does not have thereverse U extension of my invention the sediment can settle into the drain and interfere with its function. There is alsoithe possibility of there being sediment and heavy matter in stored refined oil or in gasoline. With the reverse extension no heavy matter can settle in the drain and there can be no obstruction in the drain such as will interfere with normal drainage.

The reverse extension is also functionally important in that it serves to direct the iiow of drainage from the roof toward the bottom of the tank thereby causing the drainage to settle to the bottom quicker than it otherwise would.

The invention has been in use in the oil fields and in other sections for a sufiicient period of time to satisfy the industry that it will function under conditions that would overtax the conventional drainage systems. It has been demonstrated that the trapped air does not need to be removed. It washes out with the iiow of the water. On the pontoon type of floating roof the water would draw oiI without the siphon seal because it has sufficient head above the oil, but the drain would empty itself of water and expose the liquid in the pipe (the contents of the tank) to evaporation'. With the siphon seal of my' invention that cannot occur. It is obvious that the vertical leg connecting with the root will have in it a column of water high enough to balance the pressure of the tank liquid in the other leg, but

this is true only because of the reverse bend. When the water in the vertical leg becomes higher than that necessary to balance the liquid pressure on the other leg water ows through the drain. Manifestly, if the liquid in the tank is lighter than water the levelof the water in the vertical leg will be below the roof level and the roof will be dry. Thegreater the difference in Mspecific gravity the lower thewater will stand in the leg. 'This and the length of the leg determines the number of inches orrfeet the water in the leg is below the topo! the roof. it being understood that the roof is floating on the liquid in the tank.

Without the reverse U bend no water would be held in the vertical leg. Consequently it will receive the volatiles of the tank and being open 5 at the top will losethe volatiles by evaporation and withal will present a tremendous fire hazard.

Having; described the invention, .what is claimed is:-

' 1. In storage tanks of the oat closure type, l0 the combination of a iloatingroof having a drainage collecting basin equipped with an overilow having fixed and movable pipe extensions, where- .of one is a depending drain pipe and whereof the other is a factor for priming purposes, and l5 a double U trap terminating the drain pipe, and providing Na liquid seal that is eiective to prevent rise of the liquid contents of the tank in the drain pipe.

2. In combination, a storage tank for volatiles, 20 a roof 'for oatwise support upon the contents of the tank and having a drainage sump, .and a drain pipe depending from the sump and terminating in reverse bends whereby a water column is maintained in the vertical leg to balance tank 26 pressure in the other leg. f

3. In combination, a storage tank for volatiles, a roof for floatwise support` upon the liquid contents of the tank and having a drainage sump, and a drain pipe depending from the sump and 30 continued as reversely disposed U bends effective to prevent sediment from interfering with drainage and to insure a sufcient column of water in the vertical leg to overcome or balance the tank pressure in the drain.

4. In combination, a storage tank for volatiles,

" a roof for floatwise support upon the liquid contents of the tank and having a drainage sump, and a drain comprising a straight leg depending from the sump and continued as a reverse extension having an opening directed towards the botl tom of the tank whereby a column of water is f. maintained in the straight leg to balance pressure in the extension.

5. Means, for draining floating roofs of oil storage tanks, comprising, ir'i combination, an oil storage tank, a iioating seal having a drainage collecting device, a drain pipe in communication therewith and discharging directly towards the bottom of the tank, there being a reverse connection intermediate the vertical leg of the drain and its point of discharge whereby a volatile sealing column is maintained in the vertical leg which varies according to the specific gravity of the liquid contents of the tank.

EDGAR E. sHANoR. 

